Re: [PATCH v3 09/21] sched/cache: Count tasks prefering destination LLC in a sched group

[Peter Zijlstra]

On Tue, Feb 10, 2026 at 02:18:49PM -0800, Tim Chen wrote:

> @@ -11034,6 +11037,9 @@ static inline void update_sg_lb_stats(struct lb_env *env,
>  {
>  	int i, nr_running, local_group, sd_flags = env->sd->flags;
>  	bool balancing_at_rd = !env->sd->parent;
> +#ifdef CONFIG_SCHED_CACHE
> +	int dst_llc = llc_id(env->dst_cpu);
> +#endif
>  
>  	memset(sgs, 0, sizeof(*sgs));
>  
> @@ -11054,6 +11060,15 @@ static inline void update_sg_lb_stats(struct lb_env *env,
>  		if (cpu_overutilized(i))
>  			*sg_overutilized = 1;
>  
> +#ifdef CONFIG_SCHED_CACHE
> +		if (sched_cache_enabled() && llc_id(i) != dst_llc) {

If you write that like:

		if (sched_cache_enabled && llc_id(i) != llc_id(env->dst_cpu))

You can get rid of that dst_llc variable, but more importantly its
ifdeffery.

> +			struct sched_domain *sd_tmp = rcu_dereference(rq->sd);
> +
> +			if (valid_llc_buf(sd_tmp, dst_llc))
> +				sgs->nr_pref_dst_llc += sd_tmp->pf[dst_llc];
> +		}
> +#endif